The present invention relates to a circuit substrate having high density patterns.
Conventionally, a circuit: substrate of the kind referred to above is arranged as shown in FIG. 5 of the attached drawings, for example. In FIG. 5, a circuit substrate 1 comprises a predetermined configuration at a surface of a printed board 2, that is, an electronic-part mounting or packaging section 4 arranged in one direction (in a lateral direction in an illustrated case) and a circuit 3 having a plurality of conductive patterns 3a which extend in parallel relation to each other along the electronic-part packaging section 4. Bonding wires 5 are used at respective connections of the circuit 3, that is, with respect to respective bonding pads 3b, whereby connecting terminals (not shown) of an electronic part 6 are electrically connected to the circuit 3.
By the way, in the circuit board 1 arranged as described above, wire bonding with respect to the conductive patterns 3a is performed in such a manner that the bonding pads 3b must be lengthened in a direction the same as that of the bonding wires 5, in order to crimp or pressure-bond the bonding wires 5 and to form stable loops. For this reason, there is nothing to arrange the circuits 3 by a necessary minimum length L' for pressure-bonding the bonding wires 5 of the respective bonding pads 3b and a pitch of gaps L.sub.1 ' between the adjacent conductive patterns 3a. Thus, it is difficult to increase the density of the circuit 3.
Further, as shown In FIG. 6, if a distance between the conductive pattern 3a to be connected by the wire bonding and the electronic part 6 is relatively long, a loop of the bonding wire 5 is not stabilized, and overhangs occur. Accordingly, there is a case where the bonding wire 5 is in contact with other conductive patterns 3a which are stridden by the bonding wire 5. As a result, there is a case where failure occurs due to wiring short-circuit.
Moreover, if the bonding pad 3b is lengthened by dimension corresponding to the overhang of the bonding wire 5 such that the bonding wire 5 and other conductive patterns 3a over which the bonding wire 5 strides are not short-circuited to each other, there occurs a disadvantage that the density of the circuit 3 is further reduced.